用户登录只有第一条数据成功，只能查询到第一条数据

实现用户登录功能



四条数据，只有第一条可登陆成功

原因是：

sql = "select*from manager";

应为

              sql = "select*from manager where username='"+username+"'and password='"+password+"'";

response.setContentType("test/html;charset=utf-8");
response.setCharacterEncoding("utf-8");
// 获取jsp中填入数据
String username = request.getParameter("username");
String password = request.getParameter("password");
// 数据库相关
String Dusername = null;
String Dpassword = null;
int Did = 0;
String sql = null;
// 与数据库建立连接
try {
Class.forName("com.mysql.jdbc.Driver");
System.out.println("Loading Database success");
} catch (Exception e) {
System.out.println("Class not found exception");
}
String url = "jdbc:mysql://localhost:3306/Creation";
Connection con = null;
Statement stmt = null;
ResultSet rs = null;

try {
con = (Connection) DriverManager.getConnection(url, "root", "");
stmt = (Statement) con.createStatement();

sql = "select*from manager where username='"+username+"'and password='"+password+"'";
rs = stmt.executeQuery(sql);
while (rs.next()) {
// 因为不止一个数据，就要循环，对每条数据都进行验证匹配
Dusername = rs.getString("username");
Dpassword = rs.getString("password");
System.out.println(Dusername);
System.out.println(Dpassword);
if (username.equals(Dusername) && password.equals(Dpassword)) {
System.out.println("manager登陆成功");
// 要成功，跳转success.jsp
response.sendRedirect("success.jsp");

}
else if (username.equals("admin") && password.equals("admin")) {
System.out.println("super manager登陆成功");
// 要成功，跳转success.jsp
response.sendRedirect("manager.jsp");
return;
}
else {
System.out.println("登陆失败");
response.sendRedirect("fail.jsp");
return;
}
}
} catch (Exception e) {
e.printStackTrace();
}
}